The present invention relates to a new and improved mating electrical contact structure characterized by zero or low mating insertion forces and by gradually increasing cam-assisted normal contact forces. More particularly, it relates to a mating electrical contact structure including opposed cantilevered double-pronged or bifurcate female contact terminal having outer cam surfaces at the free ends thereof and a triple-pronged or trifurcate male terminal having a central contact post and a pair of outer posts with cam surfaces which cooperatively engage female camming surfaces to increase the normal contact forces of the female contact portions on the central male contact post during final stages of mating.
Matable electrical contacts typically comprise a plug or male terminal and a socket or female terminal. The female terminal may define a bifurcate contact which comprises a pair of spaced apart cantilevered contact beams. Female terminals of this type frequently are referred to as tuning fork contacts. The cantilevered contact beams of the prior art bifurcate contacts typically include portions which are spaced from one another by a distance that is less than the width of the male terminal. As a result, the insertion of the male terminal between the contact beams of the prior art bifurcate contact will initially bias the contact beams of the female terminal away from one another. Conversely, the contact beams of the prior art bifurcate contact each will exert a normal force on the plug. Continued mating insertion movement of the make into the prior art bifurcate female will require the frictional forces between the contact beams and the male terminal to be overcome. Additionally, throughout this movement, the normal force between the contact beams of the prior art bifurcate contact and the male terminal will remain substantially constant.
The above described prior art combination of a bifurcate contact and a male terminal suffers several deficiencies. In particular, the normal force exerted by the contact beams of the prior art bifurcate female terminals are substantially at their maximum when the male terminal is initially inserted into the socket. These normal forces of the contact beams create a significant likelihood of damage to the small and usually fragile contact members during the initial insertion. Furthermore, the frictional force exerted during the insertion process is potentially damaging to both the male terminal and the contact beams of the prior art contact assembly. Furthermore, the typical prior art bifurcate contact and male terminal assembly maintains a substantially constant force throughout the entire insertion process. Thus, attempts to minimize the liklihood of damage at the initial stages of the insertion generally result in a less than desirable normal force between the contact beams of the female and the male terminal upon complete insertion, with a resulting detrimental effect on the quality of the electrical connection.
Many varities of zero insertion force connectors have been developed to address the above described problems associated with the insertion of a relatively fragile male terminal into a similarly fragile dual-cantilever spring arm female. The typical prior art zero insertion force connector includes a complex housing having a plurality of parts that are movable relative to one another. A plurality of female terminals typically are mounted in one member of the housing of the prior art zero insertion force connector. These female terminals are disposed to permit the male pin terminals to be fully seated in the housing without contacting the corresponding sockets. An actuator of the housing then is moved to urge the male and female terminals into a secure electrical connection with one another. Although prior art zero insertion force connectors work extremely well, these types of connectors tend to be relatively complex and expensive.
In view of the above, it is an object of the subject invention to provide a mating electrical contact structure that achieves a secure electrical connection with little or no insertion force exerted upon either contact.
Another object of the subject invention is to provide a mating electrical contact structure that achieves high normal forces with little likelihood of damage occurring during insertion.